Catalytic Reactor

ABSTRACT

A catalytic reactor ( 40 ) comprises a plurality of sheets ( 42 ) defining flow channels ( 44 ) between them. Within each flow channel ( 44 ) is a foil ( 46 ) of corrugated material whose surfaces are coated with catalytic material apart from where they contact the sheets ( 44 ). At each end of the reactor ( 40 ) are headers to supply gas mixtures to the flow channels ( 44 ), the headers communicating with adjacent channels being separate. The reactor ( 40 ) enables different gas mixtures to be supplied to adjacent channels ( 44 ), which may be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the sheets ( 42 ) separating the adjacent channels ( 44 ), from the exothermic reaction to the endothermic reaction. The reactor ( 40 ) may be used in a compact plant to perform steam/methane reforming, obtaining the necessary heat by catalytic methane combustion, and also for Fischer-Tropsch synthesis, so that the overall process involves conversion of methane to long-chain hydrocarbons.

This invention relates to heat exchangers. It is particularly concernedto provide a heat exchanger that can be used as a packed bed catalyticreactor.

However, it will be appreciated that the invention is not intended to belimited to use as packed bed catalytic reactors and a structure of theinvention may be used, for example, as a “bulk fluid” heat exchangerwherein one of the fluids passing through the structure comprisesgranules or powder constituents. Structures of the invention mayequally, if desired, be used to exchange heat between two liquids, twogases or between a gas and a liquid. Nevertheless, the invention willfor convenience be more particularly described with reference to packedbed catalytic reactors.

In a packed bed catalytic reactor it is necessary to pass a first fluidor mixture of fluids, which is to react in a desired manner, intocontact with a bed of a catalyst which promotes the reaction. Thereaction may be exothermic, in which case it may be necessary to coolthe reacting fluid(s), or endothermic, in which case it may be necessaryto heat the fluid(s) to promote the desired reaction. In both instances,it will be appreciated that a heat exchanger structure may usefully beemployed so that heat may be added to or taken from the fluid(s) passinginto contact with the catalytic material.

Known heat exchanger constructions for use as packed bed catalyticreactors are generally based on existing tube and shell technology andhence are not as efficient in terms of performance per unit volume aswould be reactors of more compact construction. It is, therefore, anobject of the present invention to provide an improved construction thatis particularly useful as a packed bed catalytic reactor.

Accordingly, in one aspect, the invention provides a stacked assembly ofplates, the stack having an inlet and an outlet for a first fluid and aninlet and an outlet for a second fluid, a first portion of the length ofthe assembly being formed of one or more first perforated plates, eachfirst perforated plate being perforated to define a first series ofslots spaced across the plate and a second series of slots spaced acrossthe plate, each slot of the first series being positioned between a pairof slots of the second series, whereby the slots of the first seriesdefine first passageways through the first portion of the length for afirst fluid and the slots of the second series define second passagewaysthrough the first portion of the length for a second fluid, the firstseries of passageways being connected to said inlet and outlet for thefirst fluid, a second portion of the length of the assembly being formedof one or more second perforated plates, each second perforated platebeing perforated to define a first and a second series of slotscorresponding to the slots of the first plate(s) so as to providecontinuing passageways in line with the first and second passageways ofthe first portion, each slot of the second series opening at one of itstwo ends into a feeder slot extending across the second plate, thefeeder slot(s) being connected to an inlet or an outlet for the secondfluid.

In another aspect the invention provides a heat exchanger comprising astacked assembly of plates as defined in the immediately precedingparagraph.

In a yet further aspect the invention provides a perforated plate for aheat exchanger, the plate being perforated to define a first series ofslots spaced across the plate and a second series of slots spaced acrossthe plate, each slot of the first series being positioned between a pairof slots of the second series, each slot of the second series opening atone of its two ends into a feeder slot extending across the secondplate, the feeder slot thereby connecting those first ends together

If desired, each slot of the second series of a second plate may open ateach of its ends into one of a pair of feeder slots.

In one embodiment the assembly has a third portion of its length formedat the other end of the first portion, the plate(s) of the third portionbeing of a similar construction to the plates of the second portion withthe feeder slot(s) being connected to an outlet or an inlet accordinglyfor the second fluid. In a particularly preferred embodiment, the, oreach, plate of the third portion is formed to have its feeder slotextending on the opposite side of the assembly to the feeder slots ofthe first portion, whereby the second fluid must cross the assembly fromone side to the other between the second fluid inlet and outlet.

The first fluid is conveniently the fluid to contact the catalyst whenthe structure of the invention is to be used as a packed bed catalyticreactor and the catalyst will, therefore, be packed into the firstseries of passageways through the assembly. The second fluid,correspondingly, will be a coolant or a source of heat, as required.

The plates may be of any suitable shape, e.g. they may be discs, i.e.they may be circular in plan, and the slots may be arcuate or linear.Preferably, however, the plates are square or rectangular and the slotspreferably are linear.

In another preferred embodiment, the stacked assembly may comprise firstand second length portions as described above, a baffle plate and thenanother set of first and second length portions, i.e. the baffle platelies between a pair of adjacent first length portions and the end ofeach first length portion away from the baffle plate is in contact witha second length portion.

The baffle plate may, for example, contain a series of slotscorresponding to and in line with the first series of passageways forthe first fluid so that the first fluid has an uninterrupted flowthrough the assembly and a second series of staggered slots whichpartially interrupt flow through the second series of passageways andthereby cause some at least of the coolant or heating fluid to travelnon-linearly between the two halves of the assembly divided by thebaffle plate. Baffle plates may be placed at any position or frequencyin the stack according to design and flow distribution requirements.

In another preferred embodiment of the invention, the assembly of platesincludes at one or each end thereof a perforated closure plate. Theclosure plate may, for example, have a first series of slotscorresponding to the first passageways, whereby the first fluid can flowuninterrupted through the closure plates, but no slots corresponding tothe second passageways, whereby the second fluid is diverted into theinlet and/or outlet provided into or out of the second plate(s).

Conveniently all the plates may be of the same external dimensions inplan so that they can be readily assembled together to provide thedesired passageways through the assembly. The plates may convenientlyall be of the same thickness, e.g. from 1 mm to 12 mm. However, this isnot essential and it may be found advantageous in particularcircumstances to use plates of different thickness in the assembly.

The plates may be brazed or bonded together to form the stack. Forexample, the plates may be of clad aluminium or of stainless steel. Therequired. perforations may be cut, for example, by high pressure waterjet or by etching, blanking or laser cutting. The perforated plates canthen be vacuum brazed or bonded together and any required inlet andoutlet connections and tanks can be welded to the bonded stackedassembly.

It will be appreciated that each perforated plate will have a solidperipheral region extending around its perimeter and that each slot willbe surrounded by a solid region of plate except at the open ends of thesecond slots where they open into the feeder slot. Adjacent solidregions extending between adjacent pairs of first slots may, therefore,need to be connected together by one or more strengthening tie barsextending across an intervening second slot. One such a tie bar mayconveniently be positioned towards the open end of the second slot.

Similarly, the feeder slot, which may extend along almost the entirelength of one side of a rectangular plate, may be defined inside a solidedge portion along one edge of the plate. If it is desired to feed intothe second fluid inlet from a side of the plate, then a gap must beprovided in the solid edge portion for that purpose, thereby providingan inlet into the feeder slot. However, this may not be necessary if itis desired to feed into the feeder slot in the direction of thethickness of the plate rather than transversely to that direction. If agap is provided in the solid edge portion, then one or more tie bars maybe needed, preferably adjacent that gap to connect the solid edgeportion to a solid region extending across the plate between an adjacentpair of slots.

Whether or not tie bars will be needed will be determined by therigidity of the perforated plates and hence will be determined by theirmaterial and their thickness. It will be appreciated that in order tobond the stack together conveniently, there should be little or no unduemovement of any solid regions of the plate out of the plane of the plateduring handling.

Where one or more tie bars is necessary in the second plates, it will benecessary to utilise at least two different second plates. Although theymay be essentially of the same slotted construction, they differ in thepositioning of their tie bars so that when two such second plates arestacked together, although their feeder slots and first and secondpassageway slots respectively align with each other, their tie bars areoffset from each other. By this means, fluid can flow over the tie barswhereas if the tie bars were located together, flow through the stackwould be prevented.

Injection plates may be provided in the stack whereby one or morefurther fluids can be injected into the first fluid as it passes throughthe stack. A typical injection plate may be a modified first type ofplate in which an injection channel is provided in the form of a grooveextending only partially into the thickness of the plate. The groove mayextend from an edge of the plate to pass adjacent the ends of the firstslots that lie towards that edge of the plate and then branch groovesfrom the main groove may extend into each slot. Because the groove doesnot extend completely through the thickness of the plate it will besealed by contact between that plate and solid regions of an adjacentplate in the stack.

In another embodiment, pressure equalisation means may be providedbetween the first passageways defined by the first series of slots. Thismay be particularly useful where the heat exchanger is to be used as apacked bed catalytic reactor and the catalyst is packed into those firstpassageways. By use of such pressure equalisation means, reactionquality across the whole of the reactor can be more consistent, therebyproviding greater efficiency.

The pressure equalisation may be achieved by any convenient means. Forexample, the rows of slots of the first series may be joined together attheir ends providing in effect a single continuous slot of serpentineform. Alternatively, venting may be provided between adjacent pairs offirst slots. Such venting may conveniently be provided through arrays oftie bars, each array extending in spaced formation along the length ofeach second slot and each tie bar of the array running across its secondslot from one first slot to an adjacent first slot. A venting channelmay be etched partially or otherwise formed into the thickness of eachtie bar whereby a portion of the fluid passing through a passagewaydefined by one series of stacked first slots may vent through to apassageway defined by another series of stacked adjacent first slots.

Embodiments of the invention will now be described by way of exampleonly with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic elevation of a packed bed catalytic reactor ofthe invention;

FIG. 2 is a plan view of a first type of perforated plate for use in thereactor of FIG. 1;

FIG. 3 is a plan view of one second type of perforated plate for use inthe reactor of FIG. 1;

FIG. 4 is a plan view of another second type of perforated plate for usein the reactor of FIG. 1;

FIG. 5 is a baffle plate for use in the reactor of FIG. 1;

FIG. 6 is a closure plate for use in the reactor of FIG. 1;

FIG. 7 is a view in the direction of arrow VII-VII of FIG. 1;

FIG. 8 is a view in the direction of arrow VIII-VIII of FIG. 1;

FIG. 9 is a plan view of a further type of plate for use in theinvention;

FIG. 9A is a section on line IX-IX of FIG. 9;

FIG. 9B is an enlarged view of area I of FIG. 9;

FIG. 10 is a diagrammatic elevation of an assembly of the inventioncomprising a plurality of stacks of plates with injection features;

FIG. 11 is a plan view of a yet further type of plate for use in theinvention;

FIG. 12 is a plan view of a second type of perforated plate in which theslots of the first series are joined to form a continuous single slot;

FIG. 13 is a plan view of a first type of perforated plate in whichventing is provided between adjacent pairs of first slots;

FIG. 14 is a section on line XIV-XIV of FIG. 13;

FIG. 15 is a plan view of another first type of perforated plate inwhich venting is provided between adjacent pairs of first slots;

FIG. 16 is a plan view of another first type of perforated plate inwhich venting is provided between adjacent pairs of first slots;

FIG. 17 is a plan view of an alternative first type of perforated platefor use in the invention;

FIG. 18 is a plan view of a circular closure plate for use in a stackwith a circular first type of plate;

FIG. 19 is a plan view of a circular second type of plate;

FIG. 20 is a plan view of a modified circular second type of plate;

FIG. 21 is a plan view of a circular first type of plate;

FIG. 22 is an injection plate for use in the stack with the plates ofFIGS. 18 to 21;

FIG. 23 is a perspective view of a packed bed catalytic reactor of theinvention formed from plates of FIGS. 18 to 21;

FIG. 24 is a plan view of another form of end closure plate;

FIG. 25 is a diagrammatic representation showing the coolant, i.e.second fluid, flow paths through a reactor of the invention;

FIG. 26 is a diagrammatic representation showing the flow paths forinjected fluid through the reactor; and

FIG. 27 is a plan view of a portion of another second type of plate ofthe invention.

In FIG. 1 a packed bed catalytic reactor is formed of a stacked assembly10 of perforated plates. The individual plates are described in greaterdetail below with reference to FIGS. 2 to 6.

The stack has an inlet end 12 and an outlet end 14 for flow therethroughof a first fluid which is to pass in the direction of arrow A. (Asdescribed below with reference to FIGS. 7 and 8, the passageways throughwhich the first fluid flows are packed with a catalyst.).

At the lower outlet end of the stack is a mesh cover 16 to retain thecatalyst whilst allowing fluid through flow. Immediately above mesh 16is a closure plate 18, which is described in more detail below withreference to FIG. 6.

Stacked in succession above closure plate 16 are, firstly, a second typeof perforated plate 20, a modified second type of perforated plate 22and another second type of perforated plate 20A, identical to plate 20.Plates 20, 20A and 20 form the aforesaid second portion of the length ofthe assembled stack and provide an inlet 24 for a second fluid, e.g. acoolant, into the stack. Plates 20 and 22 are described in more detailbelow with reference to FIGS. 3 and 4 respectively.

Immediately above plate 20A are four identical first type of perforatedplates 26, forming the aforesaid first portion of the length of theassembled stack. A plate 26 is described in more detail below withreference to FIG. 2.

Above plates 26 is a baffle plate 28, described in more detail belowwith reference to FIG. 5.

Above baffle plate 28 is a further assembly of five first type ofperforated plates 26A. Plates 26A are identical to plates 26.

Above plates 26A is a further assembly of another second type ofperforated plate 30, a modified second type of perforated plate 32 andanother second type of perforated plate 30A, identical to plate 30.Plates 30, 32 and 30A provide an outlet 34 for the second fluid from thestack.

Plates 20 and 30 are identical in construction except that they arerotated through 180° in the plane of the plates relative to each other.Plates 22 and 32 are also identical except that they are rotated through180° with respect to each other.

The first type of perforated plates 26 are as illustrated in FIG. 2.Each plate is rectangular in plan and has a first series of linear slots36 through its thickness. Each slot 36 extends from adjacent one edge 38to adjacent an opposite edge 40 leaving unperforated margins 38′ and 40′respectively inside those edges. The series of slots 36 extends acrossthe plate between opposite edges 42 and 44. Each plate also has a secondseries of linear slots 46 through its thickness. Each slot 46 extendsbetween edges 38 and 40 of the plate inside margins 38′ and 40′ and theseries of slots 46 also extends across the plate between edges 42 and44.

As shown, each first slot 36 lies between a pair of second slots 46 andthe slots nearest edges 42 and 44 are both second slots 46, which lieinside margins 42′ and 44′ respectively at those edges. Thus the platehas a continuous solid margin 38′, 42′, 40′, 44′ around its peripheryand margins 38′ and 40′ are also joined together by lands 48 lyingbetween adjacent pairs of slots.

The slots 36 and the slots 46 of plates 26 form respective passagewaysfor the first fluid and the second fluid when the plates are stackedtogether.

One second type of plate 20 is shown in FIG. 3. Plate 20 is alsorectangular in plan and has a first series of linear slots 36A identicalto the slots 36 in plate 26. Plate 20 also has a second series of slots46A corresponding in size and location to slots 46 of plate 26. Slots36A and 46A lie inside a solid peripheral margin 38A′, 42A′, 40A′, 44A′between edges 38A, 42A, 40A and 44A of the plate. However, althoughmargins 40A′ and 40A and 44A′ and 44A are identical, margins 38A′ and42A′ of plate 20 are different from margins 38A and 42 of plate 26.

Margin 38A′ of plate 20 is formed as a depending leg from margin 44A′and a feeder slot 50 is formed in the plate to extend parallel to edge38A and between margin 38A′ and the ends of slots 36A and 46A. Dependingleg or margin 38A′ is tied to the lowermost land 48A between the slots46A and 36A nearest to edge 42A by a tie bar 52.

Each slot 46A would open into feeder slot 50 except that a tie bar 54 isformed between each adjacent pair of lands 48A between adjacent slots tomaintain adequate rigidity of the plate. The lowermost land 48A adjacentmargin 42A′ is also joined to margin 42A′ by a tie bar 56 and theuppermost land 48A is similarly joined to margin 44A′ by a tie bar 58;As shown, all the tie bars are positioned across their respective slots46A towards the end of their slot nearest to feeder slot 50.

Margin 42A′ is provided with a gap 60 adjacent margin 38A′ whereby aninlet 62 is formed into the stack for a second fluid. (It will beappreciated that gap 60 could be positioned anywhere along the edges 38Aor 42A as its purpose is to feed into feeder slot 50 and the lowermostslot 46A.).

It will also be appreciated that an assembly of one or more plates suchas plate 20 in direct contact with one or more plates such as plate 26would prevent flow of second fluid into the feeder slot 50 and soprevent flow into slots 46A and thence slots 46. A modified type ofsecond plate, perforated as shown in FIG. 4, is therefore utilised.

In FIG. 4 plate 22 is similar to plate 20 in that it has identicalseries of slots 36B corresponding to slots 36A and slots 46Bcorresponding to slots 46A. It also has a feeder slot 50B adjacent oneedge 38B and a gap 60B in edge 42B to form an inlet 62B. Plate 22 isalso provided with tie bars for the same reason as in plate 20. Thus tiebars 54B are formed one in each slot 46B but spaced further from feederslot 50B then tie bars 54 are from feeder slot 50. Similarly a tie bar56B extends across lowermost slot 46B to join it to peripheral margin42B′ of the plate 22 and a tie 58B extends across uppermost slot 46B tojoin it to peripheral margin 44B′. Tie bars 56B and 58B are postponedfurther from inlet 62B and feeder slot 50B respectively than are theircounterparts in plate 20. Finally margin 38B′ is joined to a land 48B bya tie bar 52B. This land 48B is the second such land in from the edge42B′ of the plate whereas in plate 20 tie bar 52 joins leg 38A to thefirst land 48A adjacent edge 42A.

Thus all the respective tie bars in plates 20 and 22 are offset and, asdescribed in more detail below with reference to FIGS. 7 and 8, thisenables through flow of the second fluid through the stack.

Baffle plate 28 is shown in FIG. 5. Plate 28 has a first series of slots66 of size and position corresponding to slots 36 of plate 26, 36A ofplate 20 and 36B of plate 22. Thus flow of the first fluid through theseplates in the stack is unimpeded. However, instead of a second series ofslots corresponding to slots 46, 46A and 46B of plates 26, 20 and 22,baffle plate 28 has two series of slots 68 and 70. Each slot 68 or 70 isapproximately half of the length of each slot 46, 46A or 46B. Slots 68extend from a peripheral solid margin 72 at the right hand side of theplate as shown to the centre of plate and slots 70 extend from aperipheral solid margin 74 at the left hand side of the plate to thecentre. Slots 68 and 70 are staggered across the plate from one edge 76to the opposite edge 78 whereby each slot 66 has a slot 68 extendingfrom one of its ends for half the length of one of its longer sides andanother slot 70 extending from its other end for half of the length ofthe other of its longer sides. Thus the channels formed in the stack bythe successive slots 46 in plates 26 are alternately blocked for halftheir length and the second fluid flow is forced to take a part-sinuouspath to travel from one side of the baffle plate to the other. This isillustrated by the double-headed arrows in FIG. 1.

The closure plate 18 used at each end of the stack is shown in FIG. 6.It has a first series of slots 86 corresponding to slots 36, 36A, 36Band 66 of plates 26, 20 22 and 28 respectively so that flow of firstfluid through the stack is not interrupted. However, plate 18 has solidunperforated lands 88 between slots 86 and has solid, unperforatedmargins 90 all around its periphery. The second fluid flow channelsformed by slots 46, 46A and 46B are, therefore, closed off at each endof the stack and the second fluid flows into the stack via inlet 24(formed by gaps 60 and 60B and inlet portions 62 and 62B of two plates20 and one plate 22) and flows out of the stack via a similarly firmedoutlet 34 (see FIG. 1).

In FIG. 7, plate 20A can be seen. This lies directly above plate 22 andthen plate 20, which is identical to plate 20A. (The same referencenumerals are, therefore, used for the constituent parts of the plates 20and 20A.).

The channels formed by the first series of slots (36A in plate 20A) arepacked with catalytic material 92 to promote reaction of a first fluidpassing through those channels. The second series of slots havestaggered tie bars 54 and 54B from plates 20A and 22 respectively (eachwith a second tie bar 54 in plate 20 hidden below and spaced from theshown tie bar,54), staggered tie bars 56 and 56B (again with anotherhidden, spaced tie bar 56) and staggered tie bars 52 and 52B (again withanother hidden tie bar 52).

The second fluid flows in at inlet 60 (and 60B and a further 60 in thelower plate 20) and because of the staggering of the tie bars can flowpast the tie bars as indicated by the arrows to pass along the feederslot 50 and into each channel formed by slots 46A. The second fluid can,thereby, flow through he stack in good heat exchange contact with thefirst fluid which is flowing axially in the opposite direction.

FIG. 8 shows the outlet 34 arrangement at the opposite end of the stackto FIG. 7. Plate 30A is identical to plate 20A but is positioned in thestack rotated through 180° relative to plate 20A. Similarly, immediatelybelow plate 30A is a plate 32 identical to plate 22 but rotated through180° and immediately below plate 32 is another plate 30, identical toplate 20 but also rotated through 180°. (The constituents of plate 30Abeing identical to those of plates 20 and 20A are marked with the samereference numerals.).

Flow of second fluid is again indicated by the arrows and passes fromthe channels which include slots 46A and the feeder slot 50, via the tiebars to outlet 34.

In FIG. 9 is shown a plate 100 which enables injection of fluid e.g. airor reactant, into the first fluid in the first passageways.

Plate 100 has a series of first slots 102 corresponding to slots 36, 36Aand 36B in the above-described plates 26, 20 and 22 respectively. Thuswhen positioned in a stack of plates such as plates 26, 20 and 22, plate100 offers no obstruction to through flow of first fluid. (Catalyst may,of course, be packed into the passageways formed by slots 102, 36, 36Aand 36B.).

Each first slot 102 lies between a pair of injection grooves 104 andeach groove 104 opens into a feeder groove 106 into which fluid can beinjected via a groove inlet 108. The grooves extend only partially, e.g.halfway, into the thickness of the plate so that they are closed off bythe remaining thickness of the plate from the second channels in thenext plate in a stack.

Lands 110 between adjacent slots 102 and grooves 104 are provided withspaced grooves 112 which may similarly be, for example, of depth equalto half the thickness of the lands, as shown in FIG. 9A. Injected fluidcan, therefore, travel from inlet 108 via feeder slot 106 into eachgroove 104 and then via grooves 112 into each slot 102 as indicated bythe arrows.

It will be appreciated that plate 100 can only be used next to an entryor exit region of a stack as an end plate having solid closure regionscorresponding to and covering grooves 104 and 112 is needed to containthe injected fluid in the grooves.

In order to obtain uniform distribution of injected fluid in all thegrooves 104, it is necessary to provide a form of restriction into thegrooves nearest to the inlet 108. One form of restriction is shown inFIG. 9B and takes the form of a local restriction or narrowing of thegroove at 104A. The nearer the groove is to the inlet 108, the greateris the restriction so that the groove furthest from the inlet may haveno such restriction. In an alternative embodiment the injection groovesthemselves may be wider, the further they are from the inlet.

In FIG. 10 is shown a catalytic reactor or heat exchanger assemblycomprising four stacks of plates, i.e. stacks 121, 122, 123 and 124. Theends of each stack have a closure plate 125 e.g. of the type shown inFIG. 6.

First fluid flows through the stack from an inlet end 126 to an outletend 127.

Each stack 121 to 124 comprises an assembly of first and second typeplates as described above between its end closure plates and each stackhas an inlet 128 and an outlet 129 for second fluid.

Thus second fluid, e.g. coolant, can enter at the lowest inlet 128 andleave at the lowest outlet 129, thereby cooling the lowest stack 124.Separate coolant flows through inlets 128 and outlets 129 to each of theother stacks 123, 122 and 121 ensure that a long heat exchanger stillhas adequate cooling (or heating if desired) over its whole length.

Centrally positioned in each stack 121, 122, 123 and 124, lies aninjection plate of the type described below with reference to FIG. 11.Each such injection plate has an inlet 240 through which injected fluidmay be mixed with the first fluid flowing through the assembly.

Adjacent the inlet end of each stack 121, 122, 123 and 124, lies aninjection plate of the type described above with reference to FIG. 9.These plates have an inlet 138, which also enables injection of a fluidinto the first fluid flowing through the assembly.

In FIG. 11 is shown a form of plate 200 which enables injection of fluidinto the first fluid in the first passageways at any position along thestack, e.g. as indicated above with reference to inlets 240 in FIG. 10.

Plate 200 has a first series of slots 202 corresponding to slots 102 ofFIG. 9. Thus when positioned in a stack of plates such as plates 26, 20and 22, plate 200 offers no obstruction to through flow of first fluid.(Again, catalyst may be packed into passageways formed by the stackedslots 202, 36, 36A and 36B.).

Each first slot lies between a pair of second slots 204 which in a stackform passageways with corresponding second slots through which secondfluid may pass. Each second slot 204 has a plurality of tie bars 206spaced along its length.

An inlet 208 for injected fluid is provided at one edge 200A of theplate. This leads to an injection feeder groove 210 extending parallelto the edge 200A. Feeder groove 210 has a number of branches 212, onebranch corresponding to and leading into each first slot 202 wherebyinjection fluid can be introduced into the first slots. Again it may bedesirable to provide restrictions on the feeder branches in a similarmanner as described above with reference to FIG. 9 so as to provideuniform distribution of injected fluid. As with FIG. 9, the grooves maybe of depth equal to, say, half of the thickness of the plate. It willbe appreciated that in a stack these grooves will be closed to containthe injected fluid by the corresponding solid border region of theadjacent plate.

It will also be preferable to use plates 200 in pairs rotated through180° with respect to each other so that improved distribution isobtained by means of injection from opposite sides of the stack.

In FIG. 12 a second perforated plate 250 has a series oflongitudinally-extending first slots 252 joined into a continuous singleslot by curved perforation portions 253 joining the ends of adjacentslots. Of course, these joining perforations need not be curved but maybe linear and thereby provide a pair of right-angled bends betweenadjacent slots. Each longitudinal slot portion 252 lies between a pairof second slots 254, each second slot being sub-divided into a pluralityof sub-slots by tie bars 258. Feeder slots 260, 262 for second slots 252are positioned one adjacent each opposed edge 264, 266 of the plate toprovide access into the second fluid passageways formed by the secondslots in a stack of the plates. (As explained above, these secondperforated plates are stacked in pairs with the tie bars of one plateoffset with respect to those of the other plate.).

The provision of slots 252 as a continuous slot encourages equalisationto take place of any pressure differences in the first fluid flowingthrough the stack.

In FIGS. 13 and 14 a first perforated plate 270 has a first series ofslots 272 and a second series of slots 274. Each slot 274 is sub-dividedinto a number of smaller slots by tie bars 278. In each second series ofslots that lies between adjacent first slots, each tie bar has beenetched partway through its thickness to form a vent passage 280extending between adjacent first slots 272. Vent passages 280 provideanother means whereby first fluid pressure in the first passagewaysacross a stack of plates of the invention may be equalised and theprovision of vent passages throughout the stack enables very localisedpressure differentials to be equalised. (It will be appreciated that atie bar to be etched in this manner may need to be of greater width thana corresponding tie bar that is not required to be etched.).

In FIGS. 15 and 16 is shown a pair of first perforated plates 290 and290A that co-operate together to provide vent channels or passagesbetween adjacent pairs of first slots. Each plate has a first series ofslots 292, 292A and second slots 294, 294A, the plates being identicalin this respect. Each second series of slots is sub-divided into anumber of smaller slots by tie bars 298, 298A, the tie bars beingidentically positioned in both plates.

In each second series of slots that lies between adjacent first slots,the tie bars in each plate have each had a recess 296, 296A cutcompletely through their thickness. Each recess opens at one end into aslot 292 or 292A and extends along the majority of the length of its tiebar but is closed off at its other end from the next adjacent slot 292,292A by an unremoved land portion 297, 297A respectively.

The tie bars along each second series of slots alternately have theiropen and closed ends of their recesses facing into the first slots.

The open and closed ends of the tie bars in plate 290 are the oppositeway round to those of plate 290A. Hence when the plates are stackedtogether a passageway is formed in each superimposed pair of tie barswhereby pressure equalisation of first fluid passing along the firstseries of passageways can take place between adjacent pairs of firstpassageways. Hence even very localised pressure differentials are againreadily equalised.

The recesses may be etched or cut by other means, e.g. by machining,water jet or laser jet.

In FIG. 17 is shown an alternative form of first type of plate 300.Plate 300 has first slots 302 for first fluid and second slots 304 forsecond fluid. Slots 302 have tie bars 306 and slots 304 have tie bars308. It will be noted that tie bars 306 divide slots 302 into portionsspaced uniformly along each slot whereas the positions of tie bars 308are staggered with respect to the ends of their slots, i.e. the tie barnearest to one end of its slot is nearer to that end than the tie bar atthe opposite end of that slot is to that opposite end.

Thus, if the plates of a pair of plates 300 are rotated through 180°with respect to each other in a stack of plates, tie bars 306 of thepair of plates will be aligned in correspondence with each other but tiebars 308 will be staggered. This staggering effect can be used to createextra turbulence in the second fluid as it flows through the stack andthereby obtain a greater heat exchange effect. For example, a pair ofplates 300 could be stacked one on either side of a similar third platebut which third plate has a completely uniform distribution of tie bars.In contrast, the correspondence of tie bars 306, which can be repeatedin all of the plates through the stack, divides the first slots intoindividual cells 310 into which catalyst can be packed. This structureis then particularly useful for high pressure applications wherein, forexample, a gas can be passed through the catalyst in the cells of thestack at relatively high pressure.

In FIG. 18 a circular end closure plate 400 has a solid annular outerperipheral region 401 with eight equi-spaced bolt holes 409 and fourlugs 402, 403, 404, 405 extending from its outer periphery. Lugs 403 and405, which are diametrically opposed across the plate, contain holes 406and 407 respectively for the introduction of injection fluids, which maybe the same or different, into the first fluid passing through thestack. Lug 404, which is diametrically opposed across the plate tounperforated lug 402, has a hole 408 for the entry or exit of coolant toor from the stacks.

Disposed centrally beyond region 401 is a series of linear slots 412separated by lands 413, i.e. the plate has a first series of slots forpassage of first fluid through the stack but no second series of slots.Second fluid, therefore, cannot pass through the end plate 400 butleaves or enters via second plates 500 and 500A as described below withreference to FIGS. 19 and 20.

In FIGS. 19 and 20 are shown circular plates 500 and 500A, which are tobe stacked together adjacent to closure plate 400 to provide entry orexit for coolant. Plates 500 and 500A are identical except in respect oftheir feeder slot and tie bar constructions, which will be explainedbelow. Each plate has four lugs 502, 502A; 503, 503A; 504, 504A; and505, 505A respectively extending from its perimeters 509, 509Acorresponding to lugs 402 to 405 of plate 400. The lugs on plates 500,500A are longer than those on plate 400 (but the overall diametersdefined by the outer extremities of the lugs are the same.). The radiusof the plates to their perimeters 509, 509A is less than the radialextent of plate 400 to the innermost periphery of each bolt hole 409.Plates 500, 500A have a solid annular region 501, 501A inside perimeter509, 509A and a central region comprising two series of slots. The firstseries of slots, 512, 512A, correspond to slots 412 of plate 400. Asecond series of slots 514, 514A extends between adjacent slots 512,512A.

Slots 514, 514A, are each sub-divided by tie bars 513, 513A into alinear row of sub-slots but it will be noted that the tie bars 513 areoffset along their respective slots compared to tie bars 513A. Each slot514, 514A opens at one end into a feeder slot 515, 515A. Again it willbe seen that feeder slots 515, 515A are each formed as a series ofsub-slots by means of tie bars 516, 516A It will also be seen that tiebars 516 and 516A are offset with respect to each other.

Lugs 503, 503A and 505, 505A each contains a hole 506, 506A; 507, 507Arespectively positioned to coincide with holes 406, 407 of plate 400whereby injected fluid may pass through the lugs of the adjacent platesin the stack.

Lugs 502, 502A are unperforated but lugs 504, 504A contain a feederinlet or outlet 508, 508A, which allows second fluid, i.e. coolant, toflow into or out of the feeder slots 515, 515A and from there into slots514, 514A. The coolant enters 508, 508A via hole 408 in plate 400 orleaves from 508, 508A to exit through hole 408.

Because tie bars 513, 513A and 516, 516A are staggered coolant can flowunder and over the cross bars of adjacent plates 500, 500A to extendcompletely along slots 514, 514A.

FIG. 21 shows a first type of plate 600 to be used in a stack with theplates of FIGS. 4, 5 and 6. This has an outer perimeter 609 of radiuscorresponding to perimeter 509, 509A and four lugs 602, 603, 604, 605extending from its perimeter. These lugs are of size and positioncorresponding to lugs 502, 502A; 503, 503A; 504, 504A; and 505, 505A.

Lugs 602 and 604 are unperforated. Lugs 603 and 605 have holes 606 and607 to allow continued passage of injection fluid.

Centrally beyond solid annular region 601 of the plate lie two series ofslots 612 and 614 corresponding to slots 512, 512A and 514, 514Arespectively. Slots 614 are subdivided by tie bars 616. A plurality ofadjacent plates 600 may be used in the stack.

FIG. 22 shows an injection plate 700 which can be positioned at adesired height in the stack to inject another fluid into the first fluidpassing through the passageways formed by the slots 612, 512, 512A and412. The plate has an outer periphery 709 of radius corresponding toperimeters 509, 509A and 609 and four lugs 702, 703, 704, 705 extendingfrom its perimeter. These lugs again are of size and positioncorresponding to the lugs of plates 500, 500A and 600. Lugs 702 and 704are unperforated. Lug 703 has a hole 706 to allow one injected fluid topass through plate 700 to continue to a different height in the stackbefore injection into the first fluid. Lug 705 contains an injectiongroove 707. This extends only part way through the thickness of theplate and leads towards the centre of the plate where it meets anarcuate feeder groove 708 which has branches 710 each leading into oneend of one of a first series of slots 712. The feeder groove and itsbranches also extend only partially through the thickness of the platewhereby injection fluid is contained to travel through the groove intoslots 712 by being closed above by the solid region of the adjacentplate above plate 700 in the stack. The plate has a second series ofslots 714 with tie bars 716 and the first and second series of slotsline up through the stack with their counterparts in the other plates.

A plate similar to plate 700 but with lug 707 ungrooved and the groovedinjection arrangement provided in lug 703 in place of hole 706 can beused further down the stack to introduce another injected fluid, or moreof the same injected fluid.

In FIG. 23 a packed bed catalytic reactor 800 is made up as a stack ofplates of the types shown in FIGS. 18 to 22. It has an upper end plate400 and a similar lower end plate 400. Stacked between those plates, butnot individually visible, are firstly an upper pair of second plates500, 500A and then a stack of first plates 600. A pair of injectionplates 700 are positioned, one each at a different height in the stackof first plates. Beneath the lowermost first plate is another pair ofsecond plates 500, 500A and then the lower plate 400. The lugs of theplates combine to form four columns 802, 803, 804 and 805 extendinglongitudinally on the exterior of the stack. Column 802 is formed fromlugs 402, 502, 502A 602 and 702 and has no flow channel within it.Column 803 is formed from lugs 403, 503, 503A, 603 and 703 and has aninjection flow channel provided by holes 406, 506, 506A and 606 leadingto an injection feeder groove 707 in a plate 700 as described above.Column 804 is formed from lugs 404, 504, 504A, 604 and 704 and has asecond fluid, i.e. coolant, feeder channel provided by holes 408 andchannels 508 and 508A. Column 805 is formed from lugs 405, 505, 505A,605 and 705 and has an injection flow channel provided by holes 407,507, 507A, 607, 707 leading to another injection groove in another plate700.

The assembly can be bolted into pipe/flange assemblies using long boltspassing through corresponding pairs of holes 409 in the two end platesor by conventional nuts and bolts.

First fluid flows unimpeded through the reactor in the direction ofarrow A through the passageways formed by the first series of slots.These passageways may be packed with catalyst.

Coolant flows in the opposite direction as indicated by arrow B throughthe second series of passageways provided by the second series of slots.

Injected fluid flows into the stack as indicated by arrows C and D andleaves with the first fluid flow—see arrow A at the lower end of thestack.

It will be appreciated that with appropriately positioned entry and exitplates, i.e. with appropriately positioned coolant feeder channels, thecoolant flow may enter in column 804 and leave from column 802, therebycrossing the stack for greater cooling effect. It will also beappreciated that such an arrangement, rather than the use of baffleplates, is necessary when the second slots are subdivided by tie barsand the second plates are used in pairs with their tie bars offset fromeach other.

FIG. 24 shows an alternative end plate 920 having six injection ports.As with plate 401, this plate 920 has a first series of slots 922 but nosecond series of slots. It has eight equi-spaced lugs 923 to 930 whichprovide six injection inlets 933 to 938 for up to six differentinjection fluids and an inlet or an outlet, 931 for cooling fluid. Theeighth lug is unperforated.

Plate 920 when stacked with a suitable series of first, second andinjection plates provides a reactor in which the flows are as indicatedin FIGS. 25 and 26.

In FIG. 25 stack 900 is made up of an end plate 920 at each end, a pairof second plates 950, 950A adjacent each end plate and a stack of firstplates 960. Interspersed amongst the first plates (and shown in FIG. 12)are six injection plates. First fluid flows directly through the stackas indicated by arrow A. Coolant enters at the lower end of the stackand flows upwardly to leave from the upper plate 920 at the oppositeside to which it entered as indicated by arrow B.

In FIG. 26 the first fluid flow is shown as before but the coolant flowis omitted for clarity. A stack of first plates 960 includes sixinjection plates 970 at different levels, three injection inlets beingdiametrically opposed across the stack from the other three. Theinjection flows are indicated by arrows C and D. End plates 920A and920B differ in that upper plate 920B has holes in two of its lugs forthe two injected fluids whereas the corresponding lugs in plate 920A areunperforated.

Where multi-injection channels are used, the injection of fluids can becontrolled, e.g. by a microprocessor, whereby controlled additions or“doses” of a number of different fluids may be made into the processfluid, i.e. first fluid, on a programmed cycle. For example, at eachinjection point, the connection to the source of fluid to be injectedmay be via a solenoid valve which can be opened to allow injection for apredetermined time by the microprocessor. Improved chemical reactionprocesses may thereby be achieved

In a yet further embodiment where circular plan plates are used, thelength of the slots of the first and second series may be maintainedconstant rather than decreasing from the centre of the plate to theouter slots. This arrangement can increase the effective catalyst tovolume ratio in the stack, e.g. by up to 15%.

In another embodiment the slots of the first series may be subdivided bytie bars so that all or the majority of the sub-divided slots are of thesame length. Cooling channels provided by the second series of slots canbe arranged to turn to pass through the tie bars so that the coolingeffect in the stack can be spread around the sub-divided first slots togive even greater uniformity. An arrangement to achieve a similar effectis shown in FIG. 27 Here plate 980 has a first series of slots 982 whichare spaced in rows across the plate, each row except the diametricallyoutermost rows containing two separate slots separated by a land region983. Each row of first slots lies between a row of second slots 984. Thesecond slots are shown with and without tie bars 985 to indicate thevariety possible. Each second slot opens into a feeder slot 986 which isfed from an inlet (not shown) in the manner previously described.

The second slots, except for the diametrically outermost second slots,communicate into a further slot 988 which runs transversely to the otherslots along the central land region 983 thereby enabling second fluid(coolant) to be better distributed around the first fluid passagewaysdefined in a stack by the pairs of first slots. (Each pair of firstslots may, of course, be considered to be a subdivided slot.). The flowof second fluid is indicated by the arrows.

An arrangement in which the catalyst channels in the stack are of thesame size and cross-section also gives more uniform packing of thecatalyst in the reactor which can improve the quality andreproducibility of the process.

It will be appreciated that the invention is not limited to theembodiments shown. The slots may be of different length, shape andsequences, although it will be appreciate that the passing of secondfluid between the first fluid channels is important for good heatexchange. Thus, for example, the slots need not extend continuously fromadjacent one edge of a plate to adjacent the opposite edge. The inletsand outlets for the second fluid need not be positioned near to a cornerof the plate.

As indicated above, where tie bars are used across second slots, the tiebars need to be staggered, i.e. offset, from each other in at least twoadjacent second plates to allow flow to distribute completely across thesecond slots immediately after a second fluid inlet and immediatelyprior to a second fluid outlet. However, if tie bars are used acrosssecond slots in plates at other positions in the stack, they may bealigned or offset with respect to those of an adjacent plate. Where theyare aligned, i.e. they stack together, pressure drop may be reduced.Where they are offset turbulence may be increased resulting, forexample, in greater cooling effect.

It will also be appreciated that where a baffle plate is used, it willbe advantageous that the plate or plates immediately downstream of thebaffle should not have tie bars across the second slots unless they arestaggered from one plate to the next. Otherwise, distribution of thesecond fluid across the second slots downstream of the baffle plate maybe hindered or prevented.

1. A stacked assembly of plates, the stack having an inlet (12) and anoutlet (14) for a first fluid and an inlet (24) and an outlet (34) for asecond fluid, characterised in that a first portion of the length of theassembly is formed of one or more first perforated plates (26), eachfirst perforated plate being perforated to define a first series ofslots (36) spaced across the plate and a second series of slots (46) isspaced across the plate, each slot (36) of the first series beingpositioned between a pair of slots (46) of the second series, wherebythe slots of the first series define first passageways through the firstportion of the length for a first fluid and the slots of the secondseries define second passageways through the first portion of the lengthfor a second fluid, the first series of passageways being connected tosaid inlet (12) and outlet (14) for the first fluid, a second portion ofthe length of the assembly being formed of one or more second perforatedplates (20, 22, 20A), each second perforated plate being perforated todefine a first (36A, 36B) and a second (46A, 46B) series of slotscorresponding to the slots of the first plate(s) so as to providecontinuing passageways in line with the first and second passageways ofthe first portion, each slot (46A, 46B) of the second series opening atone of its two ends into a feeder slot (50, 50B) extending across thesecond plate, the feeder slot(s) being connected to an inlet (24) or anoutlet (34) for the second fluid.
 2. A stacked assembly according toclaim 1, characterised in that a third portion of the length of theassembly at the opposite end of the first portion to the second portionis formed of one or more plates (30, 32, 30A) of similar construction tothe plates of the second portion with the feeder slot(s) being connectedto an outlet (34) or an inlet (24) accordingly for the second fluid. 3.A stacked assembly according to claim 2, characterised in that the oreach plate (30, 32, 30A) of the third portion is formed to have itsfeeder slot (50, 50B) extending in the opposite side of the assembly tothe feeder slots (50, 50B) of the first portion, whereby the secondfluid must cross the assembly from one side to the other between thesecond fluid inlet (24) and outlet (34).
 4. A stacked assembly accordingto claim 1, 2 or 3, characterised in that the first series ofpassageways is packed with a catalyst (92).
 5. A stacked assemblyaccording to any preceding claim, characterised in that the plates (20,26, 22) are square or rectangular in plan and the slots (36, 46, 36A,46A, 36B, 46B) are linear.
 6. A stacked assembly according to anypreceding claim, characterised in that it comprises along the stack asecond length portion (20, 22, 20A), a first length portion (26), abaffle plate (28), a further first length portion (26A) and then afurther second length portion (30, 32, 30A).
 7. A stacked assemblyaccording to claim 6, characterised in that the baffle plate (28)comprises a series of slots (66) corresponding to and in line with thefirst series of passageways for the first fluid so that the first fluidhas an uninterrupted flow through the assembly and a second series ofstaggered slots (68, 70) which partially interrupt flow through thesecond series of passageways whereby some at least of the second fluidmust travel non-linearly between the two halves of the assembly dividedby the baffle plate.
 8. A stacked assembly according to any precedingclaim, characterised in that it includes at one or each end thereof aperforated closure plate (18).
 9. A stacked assembly according to claim8, characterised in that the perforated closure plate (18) has a firstseries of slots (86) corresponding to the first passageways, whereby thefirst fluid can flow uninterrupted through the closure plate, but noslot corresponding to the second passageways, whereby the second fluidis diverted into the inlet (24) and/or outlet (34) provided in thesecond plate(s).
 10. A stacked assembly according to any precedingclaim, characterised in that it includes a plate (100) having a seriesof slots (102) corresponding to the first series of slots (36), whereineach slot (102) lies between a pair of injection grooves (104), theinjection grooves (104) opening into a feeder groove (106) connected toan injection inlet (108), and the grooves (104) giving access into theslots at a plurality of positions (112) along each slot (102), wherebyfluid may be injected into each slot (102), the plate (100) beingpositioned next to a plate having solid closure regions corresponding toand covering the grooves (104, 106, 108, 112).
 11. A stacked assemblyaccording to claim 10, characterised in that restrictions (104A) areprovided in some of the grooves (104), the restriction (104A) beinggreater the nearer the groove is to the injection inlet (108).
 12. Astacked assembly according to any one of claims 1 to 9, characterised inthat it includes a modified first plate (200) in which one end of eachfirst slot (202) is connected (212) to a feeder groove (210) extendingacross the plate, the feeder groove (210) being connected to aninjection inlet (208).
 13. A stacked assembly according to claim 12,characterised in that it includes a pair of identical modified firstplates (200) stacked together but rotated through 180° with respect toeach other.
 14. A stacked assembly according to any one of claims 10 to13, characterised in that the grooves (104, 106, 108, 112, 208, 210,212) are of depth equal to about half the thickness of their respectiveplates (100, 200).
 15. A stacked assembly according to any precedingclaim, characterised in that all the plates are of the same externaldimensions.
 16. A stacked assembly according to any preceding claim,characterised in that the plates are from 1 mm to 12 mm in thickness.17. A stacked assembly according to any preceding claim, characterisedin that adjacent solid regions of a plate extending between adjacentpairs of first slots are connected together by one or more strengtheningtie bars (54, 54B, 206, 258, 278, 298, 308) extending across anintervening second slot (46A, 46B, 204, 254, 274, 294,304).
 18. Astacked assembly according to any one of claims 5 to 17, characterisedin that the feeder slots (50, 50B) extend almost the entire length ofone side (38A, 38B) of their respective plates (20, 22) and are definedinside a solid edge portion (38A′, 38B′) at that side of the plate. 19.A stacked assembly according to claim 18, characterised in that thesecond fluid is fed into the feeder slot (50, 50B) of a second plate(20, 22) through a gap (60, 60B) in a solid edge portion of the plate(42A′, 42B′) and a tie bar (56, 56B) is provided adjacent the gap toconnect the solid edge portion to a solid region extending across theplate between an adjacent pair of slots (36A, 46A; 36B, 46B).
 20. Astacked assembly according to claim 19, characterised in that itcomprises one or more adjacent pairs of second plates (20, 22), theplates of the pair having essentially the same slotted constructionwhereby their feeder slots (50, 50B) and first and second passagewaysare in alignment but their tie bars (56, 56B) are offset.
 21. A stackedassembly according to any preceding claim, characterised in that in atleast some of the plates (250, 270, 290, 290A) pressure equalisationmeans are provided between the first passageways defined by the firstseries of slots (252, 272, 292, 292A) in each of those plates.
 22. Astacked assembly according to claim 21, characterised in that the rowsof slots (252) of the first series are joined together at their ends(253).
 23. A stacked assembly according to claim 21, characterised inthat venting is provided through venting channels (280, 296, 296A) intie bars (278, 298, 298A) spaced along the length of each second slot(274, 294, 294A), each tie bar running across its second slot from onefirst slot (274, 292, 299A) to an adjacent first slot (272, 292, 292A)and having its venting channel formed partially through its thickness.24. A stacked assembly according to any preceding claim, characterisedin that the plates have one or more holes (328, 330) in a margin (332,334) outside the slots (326), the holes aligning in the stack (320) toprovide one or more passages (336, 338) through which a reactant may beinjected into the stack, the passages connecting to first passagewaysthrough the stack at different levels in the stack.
 25. A heatexchanger, characterised in that it comprises a stacked assembly (103,320) of plates according to any one of the preceding claims.
 26. Aperforated plate for a heat exchanger, characterised in that the plate(20, 22) is perforated to define a first series of slots (36A, 36B)spaced across the plate and a second series of slots (46A, 46B) spacedacross the plate, each slot. (36A, 36B) of the first series beingpositioned between a pair of slots (46A, 46B) of the second series andeach slot (46A, 46B) of the second series opening at one of its two endsinto a feeder slot (50, 50B) extending across the second plate, thefeeder slot thereby connecting those first ends together.